Assessing the underlying engineering of the make-or-break Tesla

Assessing the underlying engineering of the make-or-break Tesla

It doesn’t take much Googling to locate alarming headlines about the Tesla Model 3. Parts rework rates of 40 percent! Line speeds still less than half of Elon Musk’s promised rate! Never mind the hate-posting on Twitter: Stock price tumbles! Shorts pass $10 billion USD!

Is this just a case of a niche manufacturer struggling with the transition to high-volume production, or is the Model 3’s essential engineering flawed?

We’re not going to weigh in here on Tesla’s production ramp-up struggles. Rather, we’re going to dig with some folks who are highly qualified to comment on the Model 3’s product and process engineering. In other words: Is the Model 3 a well-made car?

Munro & Associates, Inc. of Auburn Hills, Michigan, is in the business of competitive teardown and analysis. They just completed a 6,000-man-hour study of the Model 3. Scattered around the Munro warehouse is a methodically exploded Tesla, quite literally in pieces. Founder and CEO Sandy Munro highlights the various engineering hits and misses.

Best Battery Pack in the Business

The Munro team struggled mightily to disassemble the Tesla pack, so Sandy wonders whether it will be as easy to repurpose for post-EV uses as those in the Bolt EV or BMW i3. The 2,170 cylindrical Panasonic cells in three modules are assembled with remarkable robotic precision. Each individual cell is glued to another and to the cooling channels. A unique low-heat ultrasonic aluminum wire-bonding process connects each cell to the cell-voltage balancing circuitry, which is also exceptionally precise—Munro measured a mere 0.2 millivolt variance between cells. “That’s staggeringly close,” Munro says, “far beyond what anybody else can do.” One curious choice: forming the protected top half of the pack in metal instead of lighter, cheaper fireproof plastic.

Heaviest-in-Class Bodywork

Despite aluminum construction of nearly everything aft of the rear bulkhead, the Tesla body structure weighs more than its size peers. That indicates Tesla is trailing the mainstream’s learning curve for stamped and welded/riveted unibody construction. “The strategy for the body is about as bad as could be,” Munro says. “It’s heavy and much more expensive than even the carbon-fiber BMW i3.” A careful study in industry best practices could dramatically slash the body’s cost and weight (benefiting range). One piece of low-hanging fruit: figure out how to assemble the body without an almost unheard-of 165 feet of pumpable body sealant. One flash of brilliance, however, is the instrument panel cross-car beam, an aluminum tube over which the plastic dash mounting structure is molded.

Space-Program-Level Electronics

Clearly Tesla employs a lot of savvy electrical engineers. Its electronic computing circuitry ranks somewhere between that of a cellphone and a Mars mission in terms of sophistication. “The controllers are much, much more advanced than anything we’ve seen, and they’re all in one location,” notes Munro of the consolidation of three or four modules to one devilishly complex circuit board. Solderless connections and extreme miniaturization might help realize cost savings (these boards are even smaller and more dense than the Model X’s), but Munro’s cost analysis on the electronics is incomplete. Another savings—where Models S and X use a Tesla-proprietary touchscreen, the 3’s is closer to a commercial laptop touchscreen.

Assembly Quality Lapses

Munro purchased two Model 3s; the teardown is of the one built in January 2018 but delivered in February due to rework. The other was built later. Panel gaps are inconsistent around the same car as well as between cars. Many gaps exceed accepted norms for any price class, though the later car shows signs of improvement. Where the hood meets the left fender on the newer car, the shapes are mismatched, suggesting either a stamping problem or an attempt to bend the hood to match. Shut either front door with the window rolled down, and it rattles. The earlier car also had an extra piece of weather stripping glued to the driver-side front window track. (This was the only example of obvious rework.)

Innovative Ventilation

The appealingly spare look of the Model 3’s dash is made possible in part by the lack of normal air vents. The ducting that aims that narrow, nearly invisible cross-car vent is unique in the car business. The air exits vent horizontally and attach to the dash to strike occupants low on the torso. Aim the vents up via a touchscreen command, and a second column of air blows vertically out of the less obvious slit just ahead of the mostly horizontal wood strip. Depending on the velocity of this air, the main airflow aims upward a little or a lot.

Is the Model 3 Profitable?

As we go to press, Munro’s final cost analysis is still a few weeks away, but preliminary analysis suggests the high-content variants being pushed now might indeed break even or make a slim profit. But the standard-battery model starts at $36,000 USD. Can enough money be saved on base models to make them profitable? “There’s nothing here that says ‘save money,’” Munro says. “I think $36,000 USD Model 3s will be rare as hen’s teeth. I don’t see how they could make money at $36,000 USD.”

Is the basic engineering sound?

Tesla nails the Silicon Valley electrical/electronics engineering better than any current competitor Munro has studied, and his team has scrutinized all the leaders. There’s also abundant and impressive innovation in this car. But its essential body structure and design-for-manufacturing engineering trail the industry. It might be time for Tesla to raid mainstream automakers’ senior mechanical and manufacturing engineering ranks.